1. Field of the Invention
The present invention relates to a variable displacement wobble plate type compressor. More particularly, the present invention relates to an apparatus for lubricating wobble plate bearings of the wobble plate type compressor.
2. Description of the Related Art
A multi-piston refrigerant compressor for use in a vehicle air-conditioning circuit is known. In such a compressor, lubricating oil is contained in the refrigerant gas for lubricating internal moving elements of the compressor during running thereof. One typical apparatus for lubricating the moving elements of a multi-piston compressor is disclosed in U.S, Pat. No. 4,070,136 to Nakayama et al, in which the internal arrangement for lubricating ball bearings and shoes connecting multi-pistons and a swash plate is provided so as to introduce oil particles suspended in the refrigerant suction gas into a swash plate chamber for rotatably mounting the swash plate therein, whereby the oil particles lubricate the ball bearings and the shoes. The known internal lubricating arrangement, however, is not applicable to a variable capacity wobble plate type compressor, because a direct introduction of the oil suspended suction refrigerant gas into a crankcase for receiving therein a wobble plate mechanism makes it impossible to control the inclination angle of the wobble plate in response to a change in a cooling load of the air-conditioning circuit.
Another typical refrigerant compressor lubrication system is disclosed in U.S. Pat. No. 4,480,964 to Skinner in which oil entrained in the refrigerant is used to lubricate critical bearing surfaces of a variable capacity wobble plate type compressor, by providing the compressor interior with a lubrication-vent path arrangement, i.e., a crank-casesuction vent formed with bleed or vent passages connecting the crankcase to the compressor suction chamber. This U.S. patent also discloses that the centrifugal action at the rotating bearing surfaces can be utilized to constantly maintain a certain amount of oil in the crankcase bottom for further compressor lubrication usage. The lubrication system of U.S. Pat. No. 4,480,964, however, is not provided with a means for preserving the oil in the proximity of the critical bearings surfaces per se arranged between a rotatable drive plate and a non-rotatable wobble plate of the variable capacity wobble plate type compressor, and as a result, lubrication of the bearing surfaces becomes insufficient during the operation of the wobble plate type compressor.